The mechanisms which underlie the symptoms of nausea and vague upper abdominal discomfort remain unknown. Disturbances in gastric electrical rhythms are associated with motion sickness symptoms especially nausea and vague upper abdominal discomfort. Cholecystokinin is considered a 'satiety hormone' and severe satiety is similar to nausea. In addition, many antibiotics including erythromycin cause nausea and upper abdominal discomfort. Therefore, the purpose of this study is to determine whether cholecystokinin and erythromycin produce gastric electrical abnormalities which are recorded during motion sickness. Myoelectrical activity will be recorded by the use of Ag-AgCl EKG type electrodes which will be placed over the upper abdomen. These studies will further our understanding of the gastric and hormonal mechanism of CCK and erythromycin-induced nausea in humans.